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Author Topic: Why is life not common in our galaxy?  (Read 2130 times)

Offline lunar11

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Why is life not common in our galaxy?
« on: 24/11/2012 20:08:43 »
There are billions of stars in the Milky Way. Surely there should be many planets in the 'goldielocks zone' and so life should be rife.


Offline CliffordK

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Re: Why is life not common in our galaxy?
« Reply #1 on: 25/11/2012 01:15:57 »
We don't really know how much life there is in the Milky Way.  Some theories would indicate that it is very abundant.

We barely have the technology to detect large, uninhabitable planets around other stars in the Milky Way.  I don't believe we have the technology to detect an exoplanet equivalent to 19th century Earth, although we may, or may soon have the technology to detect large amounts of free oxygen around a planet.

We may or may not be able to detect a 21st century Earth-like planet. 

And, while there are many theories that we have been visited by aliens, or perhaps we ARE aliens, so far the evidence of this is very sparse.  It would be a very difficult task to travel to another planet using current technology.  Even sending an unmanned probe to the nearest star would be difficult.  While one can imagine quick hops between star systems, there is no reason to believe that the trip will ever become trivial.

Offline syhprum

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Re: Why is life not common in our galaxy?
« Reply #2 on: 25/11/2012 05:19:48 »
I refute the statement that life is not common in our galaxy with what we know about how planets are formed and how we visualise the manner in which inter atomic forces lead to the formation of life it seems to me that life probably exists on at least .1% of the planets that exist around the hundreds of billions of stars in our galaxy.

Offline Soul Surfer

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Re: Why is life not common in our galaxy?
« Reply #3 on: 25/11/2012 16:02:08 »
We do not know that life is not common throughout the universe.

I expect that simple life is and it probably exists or has existed elsewhere in our solar system

However the probability of complex life requires long periods of reasonable stability and will be less common

The probability of intelligent and communicating life may be very small indeed.  Remember that The ability to produce intelligence signals capable of being detected from a distance has only existed on earth for 100 years so any intelligence more that 100 light years away cannot have heard us yet and we have only been able to send signals for about 50 years and have very seldom done so.

The other big question is how long will this intelligence and communication capacity exist.  Current predictions suggest that we (and probably other intelligent communicating life) will be lucky to last more than a few thousand years. Let alone the millions or billions of years needed to have a good probability of finding such life within 100 light years to be reasonably high.

Remember also that space is very sparsely inhabited by stars it is estimated that there are only around 10,000 stars within 100 light years compared with 100 billion on the galaxy.

Offline yor_on

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Re: Why is life not common in our galaxy?
« Reply #4 on: 29/11/2012 18:16:56 »
I'm sure there is 'life'. If we by that mean something complex enough to ponder its existence. If there are more of our type out there should depend on what type of planet it have. And that's probably why we look for 'humanoid planets', we somehow expect us able to communicate with those, or maybe just war with them :) Eh, that was a joke.. Hopefully.

Offline Don_1

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Re: Why is life not common in our galaxy?
« Reply #5 on: 04/12/2012 12:02:24 »
Who said it isn't?

Just because we haven't found it & it hasn't found us, doesn't mean it isn't there.

There are species here on Earth we haven't found yet, but they are there.

The problem is we can't see or reach far enough to detect life on other planets and if we are unable to do so, then I would say there is good chance that the same applies to life elsewhere.

Offline a_dark_knight

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Re: Why is life not common in our galaxy?
« Reply #6 on: 05/12/2012 02:01:47 »
Unless I'm mistaken, this is one of the things in science we know least about. Life could be incredibly abundant or it could be rare to the point that we are completely alone. We have no context so we don't know how natural it was for life to arise here. Maybe it's inevitable for any "habitable" planet or maybe this is the only place it has ever occured.

Nor does life necessarily lead directly to "intelligent" life, they may be two independently amazing miracles. Obviously, if "intelligent" aliens are deliberately putting out messages they'll be easier to detect. What's interesting to me is the pace of our own evolution. Has it been a fairly steady, linear path? As in, was there much chance involved or was it always going to take exactly this long for us to reach this point?

It seems silly to be worried about a lack of life (or evidence for it) seeing as we literally just exploded onto the scene and have just barely started to scratch the surface of exploring the universe. What happened here was clearly quite special or else we would have popped onto the scene long ago. And considering our pace of technological progress, we'll know soon enough. Consider all the millions of years of dinosaurs eating eachother. We've got time. If other life exists, they're most definitely *way* ahead or *way* behind us.

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Re: Why is life not common in our galaxy?
« Reply #6 on: 05/12/2012 02:01:47 »


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